The present invention relates generally to voltage reference and voltage regulator circuits, and more particularly, to a bandgap voltage reference and regulator circuit with a common amplifier.
Voltage references and voltage regulators are electronic circuits that are coextensively used in electronic circuits. Bandgap based voltage references supply a constant and stable reference voltage, typically within the bandgap voltage operating point of 1.2V, to other devices in a circuit such as voltage regulators. Voltage regulators provide a constant voltage, independent of load current, for a predetermined range of load currents.
The bandgap voltage reference typically includes a bandgap core having multiple resistors in combination with multiple transistors and a gain stage to generate the reference voltage equal to the bandgap voltage of the semiconductor material. The voltage regulator receives an input reference voltage generated by the bandgap voltage reference. The voltage regulator typically includes multiple transistors with multiple output resistors in a voltage divider arrangement as load in combination with an error amplifier to regulate and maintain the output voltage. Bandgap voltage references together with voltage regulators are able to supply a voltage that is stable and self-regulated over time under varying load currents, voltage supplies and temperatures. However, the use of these two circuits in tandem as conventionally arranged is relatively expensive to implement from power and area considerations as the industry demands integrated circuit (IC) designs with ever decreasing power supplies and smaller footprints. Each circuit occupies valuable circuit area and requires significant power in space-limited and low power applications.
Accordingly, there is a need for addressing or at least alleviating some of the above limitations and problems.